optimal page replacement algorithm to find page fault

1#include<stdio.h>
2 
3int main()
4{
5    int no_of_frames, no_of_pages, frames[10], pages[30], temp[10], flag1, flag2, flag3, i, j, k, pos, max, faults = 0;
6    printf("Enter number of frames: ");
7    scanf("%d", &no_of_frames);
8    
9    printf("Enter number of pages: ");
10    scanf("%d", &no_of_pages);
11    
12    printf("Enter page reference string: ");
13    
14    for(i = 0; i < no_of_pages; ++i){
15        scanf("%d", &pages[i]);
16    }
17    
18    for(i = 0; i < no_of_frames; ++i){
19        frames[i] = -1;
20    }
21    
22    for(i = 0; i < no_of_pages; ++i){
23        flag1 = flag2 = 0;
24        
25        for(j = 0; j < no_of_frames; ++j){
26            if(frames[j] == pages[i]){
27                   flag1 = flag2 = 1;
28                   break;
29               }
30        }
31        
32        if(flag1 == 0){
33            for(j = 0; j < no_of_frames; ++j){
34                if(frames[j] == -1){
35                    faults++;
36                    frames[j] = pages[i];
37                    flag2 = 1;
38                    break;
39                }
40            }    
41        }
42        
43        if(flag2 == 0){
44        	flag3 =0;
45        	
46            for(j = 0; j < no_of_frames; ++j){
47            	temp[j] = -1;
48            	
49            	for(k = i + 1; k < no_of_pages; ++k){
50            		if(frames[j] == pages[k]){
51            			temp[j] = k;
52            			break;
53            		}
54            	}
55            }
56            
57            for(j = 0; j < no_of_frames; ++j){
58            	if(temp[j] == -1){
59            		pos = j;
60            		flag3 = 1;
61            		break;
62            	}
63            }
64            
65            if(flag3 ==0){
66            	max = temp[0];
67            	pos = 0;
68            	
69            	for(j = 1; j < no_of_frames; ++j){
70            		if(temp[j] > max){
71            			max = temp[j];
72            			pos = j;
73            		}
74            	}            	
75            }
76			
77			frames[pos] = pages[i];
78			faults++;
79        }
80        
81        printf("\n");
82        
83        for(j = 0; j < no_of_frames; ++j){
84            printf("%d\t", frames[j]);
85        }
86    }
87    
88    printf("\n\nTotal Page Faults = %d", faults);
89    
90    return 0;
91}
92