day 2 lab assignment(sort not working)

#include <stdio.h>
#include <stdlib.h>

struct term{
    int exp;
    float coef;
};


void display(struct term* poly,int,int);
void input(struct term*,int,int);
void sort(struct term*,int,int);
void add(struct term*,int,int);

int main(){
    int n1,n2;

    printf("Enter the number of term in 1st polynomial:");
    scanf("%d",&n1);
    printf("Enter the number of term in 2nd polynomial:");
    scanf("%d",&n2);

    struct term*poly=(struct term *)malloc((n1+n2)*sizeof(struct term));

    printf("Enter 1st polynomial:\n");
    input(poly,0,n1-1);
    sort(poly,0,n1-1);

    printf("Enter 2nd polynomial:\n");
    input(poly,n1,n1+n2-1);
    sort(poly,n1,n1+n2-1);

    printf("Polynomial 1 is:\n");
    display(poly,0,n1-1);

    printf("Polynomial 2 is:\n");
    display(poly,n1,n1+n2-1);

    add(poly,n1,n2);
    sort(poly,0,n1+n2-1);

    printf("Resultant polynomial is:\n");
    display(poly,0,n1+n2-1);

    return 0;
}

void input(struct term* p,int l,int r){
    int i;
    for(i=l;i<=r;i++){
        printf("TERM %d:\n",i-l+1);
        printf("Enter exponent:");
        scanf("%d",&p[i].exp);
        printf("Enter coefficient:");
        scanf("%f",&p[i].coef);

    }
}

void display(struct term* poly,int l,int r){
    int i;
    for(i=l;i<=r;i++){
        if(poly[i].coef){
            printf("%.2fx^%d",poly[i].coef,poly[i].exp);
        if(i!=r)
            printf("+");
        }

    }
    printf("\n");

}

void sort(struct term* poly,int l,int r){
    int i,j;
    struct term temp;
   // int  n=r-l+1;
    for(i=l;i<r-1;i++){
        for(j=l;j<r-i+1;j++){
            if(poly[j].exp<poly[j+1].exp){
                temp=poly[j];
                poly[j]=poly[j+i];
                poly[j+i]=temp;
            }
           else  if(poly[j].exp==poly[j+1].exp){
               poly[j].coef+=poly[j+1].coef;
               poly[j+1].coef=0;
           }
        }
    }
}

void add(struct term* poly,int m,int n){
    int i,j;
    for(i=0;i<m;i++){
        for(j=m;j<m+n;j++){
            if(poly[i].exp==poly[j].exp){
               poly[i].coef+=poly[j].coef;
               poly[j].coef=0;
            }
        }
    }

}