**Please only write code for optimal page. Don't write code for FIFO and LRU**I have uploaded the screenshot of what the input file should look like Write a program that implements the FIFO, LRU, and optimal pagereplacement algorithms presented in this chapter. First, you get a randompage-reference string where page numbers range from 0 to 9 from aninput file. Apply the random page-reference string to each algorithm, andrecord the number of page faults incurred by each algorithm. Implementthe replacement algorithms so that the number of page frames can varyfrom 1 to 7. Get this from the command line as command line argument(argv[] in main()). Assume that demand paging is used. Your programshould read input.txt from the same directory and generate output.txt inthe same directory. Formats are like below: input.txt6123413# of page referencesPage reference stringA space separates requests

CODE:- #include <stdio.h> int n, pg[20], fr[15];void FIFO();void optimal();void LRU();void main() { int i, ch; printf("\nEnter the total number of pages:"); scanf("%d", &n); printf("\nEnter the page references:"); for (i = 0; i<n; i++) //accepting sequence scanf("%d", &pg[i]); do { printf("\n\tMENU\n"); printf("\n1)FIFO"); printf("\n2)OPTIMAL"); printf("\n3)LRU"); printf("\n4)Exit"); printf("\nEnter your choice:"); scanf("%d", &ch); switch (ch) { case 1: FIFO(); break; case 2: optimal(); break; case 3: LRU(); break; } } while (ch != 4); getchar(); } void FIFO() { int i, f, r, s, count, flag, num, psize; f = 0; r = 0; s = 0; flag = 0; count = 0; printf("\nEnter size of page frame:"); scanf("%d", &psize); for (i = 0; i<psize; i++) { fr[i] = -1; } while (s<n) { flag = 0; num = pg[s]; //check wether the page is already exist for (i = 0; i<psize; i++) { if (num == fr[i]) { s++; flag = 1; break; } } //if page is not already exist if (flag == 0) { if (r<psize) { fr[r] = pg[s]; r++; s++; count++; } else { if (f<psize) { fr[f] = pg[s]; s++; f++; count++; } else f = 0; } } printf("\n"); for (i = 0; i<psize; i++) { printf("%d\t", fr[i]); } } printf("\nPage Faults=%d", count); getchar(); } void optimal() { int count[10], i, j, k, l, m, p, r, fault, fSize, flag, temp, max, tempflag = 0; fault = 0; k = 0; printf("\nEnter THE frame size:"); scanf("%d", &fSize); //initilizing frames array for (i = 0; i<fSize; i++) { count[i] = 0; fr[i] = -1; } for (i = 0; i<n; i++) { flag = 0; temp = pg[i]; //check wether the page is already exist for (j = 0; j<fSize; j++) { if (temp == fr[j]) { flag = 1; break; } } //if the page is not already exist and frame has empty slot if ((flag == 0) && (k<fSize)) { fault++; fr[k] = temp; k++; //printf("\n Test 0"); } //if the page is not already exist and frame is full else if ((flag == 0) && (k == fSize)) { fault++; for (l = 0; l<fSize; l++) { count[l] = 0; } //apply optimal replacemnt strategy for (m = 0; m<fSize; m++) { tempflag = 0; for (r = i + 1; r<n; r++) { if (fr[m] == pg[r]) { if (count[m] == 0) count[m] = r; tempflag = 1; } } if (tempflag != 1) { count[m] = n + 1; } } //find optimal page to replace p = 0; max = count[0]; for (l = 0; l<fSize; l++) { if (count[l]>max) { max = count[l]; p = l; } } fr[p] = temp; } //print the page frame printf("\n"); for (l = 0; l<fSize; l++) { printf("%d\t", fr[l]); } } printf("\nTotal number of faults=%d", fault); getchar(); } void LRU() { int count[10], i, j, k, fault, f, flag, temp, current, c, dist, least, m, cnt, p, x; fault = 0; dist = 0; k = 0; printf("\nEnter frame size:"); scanf("%d", &f); //initilizing distance and frame array for (i = 0; i<f; i++) { count[i] = 0;//helps to know recently used page fr[i] = -1; } for (i = 0; i<n; i++) { flag = 0; temp = pg[i]; //check wether the page is already exist or not for (j = 0; j<f; j++) { if (temp == fr[j]) { flag = 1; count[j] = i; break; } } //if the page is not already exist and frame has empty slot if ((flag == 0) && (k<f)) { fault++; fr[k] = temp; count[k] = i; k++; } //if the page is not already exist and frame is full else if ((flag == 0) && (k == f)) { fault++; //find the least recenlty used page least = count[0]; for (m = 0; m<f; m++) { if (count[m]<least) { least = count[m]; p = m; } } fr[p] = temp; count[p] = i; p = 0; } //print the page frame printf("\n"); for (x = 0; x<f; x++) { printf("%d\t", fr[x]); } } printf("\nTotal number of faults=%d", fault); getchar(); }OUTPUT:-